One day after the morning raids to gather evidence against Prime Minister Ehud Olmert, detectives from the Israel Police's crack National Fraud Squad returned to their usual routine of operational silence Monday concerning one of the most talked-about investigations in the country. But those familiar with the long and often painstaking process of building a white-collar case said that now the detectives' real work would begin. After spending hours in almost 20 offices gathering documents and computer hard drives on Sunday, detectives will now begin to sift through the collected materials to try to find a paper trail pointing toward a conviction. "It's not just about sorting through the papers," said Cmdr. Moshe Mizrahi (ret.), an old hand at white collar crime investigations and the former commander of the Investigations Division during the period in which then-prime minister Ariel Sharon was under investigation. "It's about familiarizing yourself with all of the material prior to a 'frontal' questioning, with a potential suspect or witness sitting in front of you." The next stage - after the evidence is both condensed and studied - is to call suspects for questioning, as well as people who may be able to provide key testimony. Mizrahi said that acquiring testimony in a case against a figure as powerful and influential as a prime minister can be challenging. "Sometimes, especially in these circumstances, people demonstrate a willingness to... take a bullet to protect the more powerful suspect," he explained. He added that because of such considerations, the paper trail that emerges from the documents seized can play a much bigger part in bringing about an indictment than can testimony. In this case, however, Mizrahi acknowledged that there were some confounding factors that influenced the prognosis for an indictment and trial in the case of Olmert. First the "foot-dragging caused no small damage" to investigators, he said, referring to the period between when the investigation was opened and when investigators raided offices for papers. In the case of the Cremieux house affair, in which Olmert is suspected of receiving a deduction of hundreds of thousands of dollars in the price of his home in return for using his influence to obtain substantial building concessions for the contractor from the Jerusalem Municipality, the investigation had been under way for months, giving suspects a chance to destroy incriminating evidence. "Anybody who wanted to prepare for winter had the opportunity to do so," Mizrahi explained. Second, he said, the scale of cronyism allegations appears to be much smaller than some already uncovered, such as the allegations leading to the indictment of MK Tzahi Hanegbi - and proving that political appointments were made on a limited scale can be tough. Similarly, aspects of the Cremieux affair, such as proving that the price was lowered with the intent of garnering Olmert's influence within City Hall decisions, will also be difficult to generate from documentary evidence. But - says Mizrahi - the police seem to be, given the circumstances, going about their job in the most professional way possible. "The raids yesterday were simply part of procedure. Had they been done differently, then there should have been criticism. But as they were - that is exactly how they are supposed to have been done."